Terror Attack| Home-made bomb on London train injures 20, including children

A 'bucket bomb' has exploded on Tube train at the height of rush hour today sending a 'wall of fire' through the carriage injuring at least 20 people including children in a suspected terror attack.

Terrified passengers 'ran for their lives' and were seen covered in blood with scorched legs, faces and hair after the incident at Parsons Green station in west London at 8.20am.

Photographs from the District Line train show what experts believe is a 'pretty unsophisticated' bomb in a flaming white bucket inside a Lidl freezer bag with Christmas lights connected to a battery protruding out of the top.

Witnesses said there was a loud 'bang', a flash and then a ball of flame engulfed the area but police believe it failed to properly detonate.

Scotland Yard sources have said that it is being treated as terrorist incident but could not confirm claims there is another device and the suspect is on the run.

But an officer at the scene told MailOnline: 'We believe there is a second bomb - there is a man with knives on the loose.'

Prime Minister Theresa May is to chair a meeting of the Government's Cobra emergencies committee this afternoon to discuss the terrorist attack.

Armed Police, paramedics and firefighters were all said to be at the west London station within five minutes of the explosion today.

A hundred metre cordon was erected around the station and a police helicopter was also overhead.

Deputy Assistant Commissioner Neil Basu, the senior national coordinator for CT policing, has declared it a terrorist incident.